Woolworths: We see a 15% energy efficiency improvement with transcritical CO2

The Australian retailer measured the performance improvement of its pilot transcritical CO2 system versus its standard R134a/CO2 cascade systems during the winter season.

Dario Ferlin, Woolworths, presents at AIRAH Refrigeration 2018

Woolworths has reported significant energy efficiency benefits after nearly a year of benchmarking performance data for its pilot transcritical CO2 system in Sydney.

"During the coldest days of the year, the energy efficiency of the transcritical system outperformed that of our current standard specification R134a/CO2 systems to the extent of around 15%," said Woolworths sustainability engineer, Dario Ferlin.

The results were presented at the Australian Institute of Refrigeration, Air Conditioning and Heating's (AIRAH) Refrigeration 2018 conference, which took place in Sydney, Australia on 26-27 March 2018.

Measurements were taken over Australia's last winter season, July through September 2017, through Australia's hottest season lasting into early 2018, with temperatures that reached 45° C.

Ferlin attributes the energy efficiency benefits to the use of adiabatic cooling.

"We’ve got adiabatic coolers on the gas coolers," said Ferlin. "There is no way around this. Transcritical systems in warm climates require adiabatic cooling.”

“

During the coldest days of the year, the energy efficiency of the transcritical system outperformed that of our current standard specification 134a/CO2 systems to the extent of around 15%."– Dario Ferlin, Woolworths

Woolworths shows promising transcritical CO2 future

Though Ferlin noted that the pilot transcritical system was "up to 10% less efficient (than their current specification 134a/CO2 systems) during the warmest days of the year, and just as efficient on the hottest days of the year," he emphasized the fact that this is the retailers first transcritical installation.

"Our pilot transcritical system is just that. It is a pilot. It's our first crack at it," said Ferlin.

"Its primary objective was to enable the store to trade. We weren’t chasing the gold standard in terms of energy efficiency. We wanted something which was reliable, robust, cost effective as much as can be and repeatable. Something which would create the framework for future iterations of transcritical systems, not only for Woolworths but for the industry."

Ferlin believes that the projected annualized data suggests that the transcritical system's energy efficiency would fall in line with its R134a/CO2 systems.

"Only two weeks ago, we did a significant reconfiguration of the parallel compressors and we expect to see some significant energy improvements," Ferlin explained.

"So, there’s a lot of room for improvement for transcritical systems. That’s the take home message."

Woolworths opened its first transcritical CO2 store, in Colebee, New South Wales on 16 May 2017. Read more about it in Accelerate Australia & NZhere.